Lift truck mast mounting



May 23, 1967 M. LINSAY LIFT TRUCK MAST MOUNTING 2 Sheets-Sheet 1 Filed April 23, 1964 PRIOR ART FIG. 2

FIG. I

PRIOR ART Fla. 3

MICHAE L LINSAY INVE NTOR AT TORNEY May 23, 1967 M. LINSAY LIFT TRUCK MAST MOUNTING 2 Sheets-$heet 2 Filed April 23, 1964 MICHAEL LINSAY INVENTOR BY ATTORNEY United States Patent Ofilice 3,321,044 Patented May 23, 1967 Filed Apr. 23, 1964, Ser. No. 362,023 11 Claims. (Cl. 187--9) This invention relates generally to lift trucks and particularly to an improved mounting arrangement for a tiltable lifting mast assembly.

Lift trucks commonly comprise a powered vehicle to the front of which is mounted a mast assembly which, in turn, guides and supports a lifting carriage. The carriage is designed to support a load and can be raised or lowered by the operator. The mast assembly is usually pivotally mounted to the frame of the truck near the bottom to enable the operator to tilt the mast a few degrees to either side of the vertical. The present invention is directed primarily to the arrangement for mounting the mast on the truck.

The mast assembly should be mounted as close as possible to the main body of the truck both to minimize the overall length of the vehicle and to minimize the moment tending to overturn the truck. Additionally, the mast as sembly should 'be readily removable to provide access to various parts of the truck and mast for servicing operations. A lift truck in normal use may require such servicing several times a year and therefore it is highly desirable that the removal of the mast consume as little time and effort as possible.

The present invention is particularly useful in connection with a front wheel drive truck in which a prime mover, such as a gasoline engine or an electric motor, is operatively connected to a mechanical differential assembly. The latter assembly includes two laterally extending shafts comprising a front axle which drives the two front wheels. In such a truck, the location of the differential housing limits the rearward position of the mast assembly.

Various mast mounting systems have been used in the past. Inone arrangement, a horizontally extending shaft fastened to the mast rests in two upwardly opening con= cave bearing members fastened to the front of the truck forward of and above the front axle. A retainer closes the opening of the bearing, holding the mast in place. This arrangement, although widely used, has the disadvantage that because the pivot axis of the mast is above the axis of the differential, the mast must be spaced forwardly of the differential housing in order to provide clearance when the mast is tilted.

In another prior arrangement, a pair of downwardly opening concave bearing members are fastened to the mast assembly and rest directly on the front axle on either side of the differential. A pair of complementary upwardly opening concave caps, or retainers, are positioned underneath the axle and bolted to the bearing members on the 'mast, thus holding the mast in place. Since the pivot axis of the mast coincides with the axis of the differential, it is possible to position the mast closely adjacent to the dif 'ferential housing. However, the location of the retainers Another object is to proivde a pivoted mast mounting structure in which the mast assembly may be positioned closely adjacent to the differential housing.

Another object is to provide a structure for pivotally mounting a mast assembly to the frame of a truck which structure enables the mast assembly to be installed and removed conveniently.

Briefly stated, a mast assembly in accordance with the invention includes, near the bottom, a pair of downwardly opening concave bearing surfaces which rest on and are supported by the front axle on either side of the differential. However, instead of retaining the mast assembly with bearing caps positioned underneath the axle, a portion of the mast assembly is formed with a pair of convex bearing surfaces above the concave surfaces. Two retainers having concave bearing surfaces complementary to and engaging the convex surfaces are removably fastened to the frame. Thus, While the mast assembly is pivoted about the axle, the retainers are in an accessible position above the axle.

For a clearer understanding of the invention, reference may be made to the following detailed description and the accompanying drawing, in which:

FIGURE 1 is a side elevation view of a lift truck includin g the present invention;

FIGURES 2 and 3 illustrate prior art arrangements for mounting a mast assembly;

FIGURE 4 is a cross sectional view illustrating the principal features of the invention taken along the line 4-4 of FIGURE 5;

FIGURE 5 is a front view of the lower portion of the truck, partly in elevation and partly in section taken along the line 55 of FIGURE 4;

FIGURE 6 is a fragmentary cross sectional view taken along the line 66 of FIGURE 5;

FIGURE 7 is an exploded pictorial view of the principal parts of the invention; and I FIGURE 8 is an assembled pictorial view of the parts shown in FIGURE 7.

Referring first to FIGURE 1 there is shown a lift truck indicated generally by the reference character 11 including a frame 12, drive wheels 13, rear steerable wheels 14, a steering wheel 15, a seat 16 and a mast assembly 17. A carriage 18 including lifting forks 19 is supported for vertical movement on the mast 17 under the control of an operator. The mast is pivotally mounted near its lower end as will be more fully explained. An hydraulic ram assembly 21 is mounted on the frame of the truck and includes a piston rod 22 mechanically connected to a bracket 23 which, in turn, is connected to the mast assembly 17. Another similar ram mechanism, not visible in FIGURE 1, is similarly mounted on the other side of the truck. The ram mechanisms may be actuated by the operator to tilt the mast assembly 17 about its pivot axis a few degrees from ,the vertical in either direction as shown by the dotted outline.

The present invention is directed primarily to the pivoted mast mounting. In order that the features and advantages of the invention may be more fully appreciated two typical prior art arrangements will be described. One such arrangement is illustrated in FIGURE 2 wherein a portion 26 of the frame of the truck is formed with a downwardly opening concave bearing surface 27 which rests on the axle 28 and is held in place by a complementarv etainer 29. The frame portion 26 has formed therein an arcuate slot 31 defining a concave bearing surface. Behind the frame portion 26 can be seen in dotted outline the position of a differential housing 32 concentric with the axle 28. On the other side of the differential housing (not visible in FIGURE 2) is another frame portion similar to the frame portion 26.

A pair of brackets 33 (only one of which is visible in FIGURE 2) are fastened to the mast assembly 17. A rod or shaft 34 is fastened to these brackets in a substantially horizontal position and rests in the slots 31. A pair of keepers 35 are removably fastened to the frame portions 26 to hold the rod 34 in place.

This arrangement is widely used for mounting a tiltable mast. The pivot point obviously is the center of the shaft 34 which is substantially above the center line of the axle 28. As the mast assembly is tilted forward (counterclockwise as Viewed in FIGURE 2) about the shaft 34, the lower end of the mast assembly 17 approaches the differential housing 32. Therefore, it is necessary to mount the assembly 17 so that when in its normal vertical position there is a substantial clearance between the mast assembly 17 and the differential housing 32. Such forward positioning of the mast assembly positions the load on the forks just that amount more in front of the wheels thereby increasing the moment tending to overturn the truck and decreasing the load capacity.

Another widely used arrangement is shown in FIG- URE 3 wherein a bracket 37 fastened to the mast assembly 17 is formed with a semi-cylindrical bearing surface 38 which rests directly on the axle 28. A complementary retainer 39 holds the bracket and mast assembly in place. With this arrangement the pivot point of the mast is at the center of the axle 28, concentric with the differential housing 32, so that it is possible to position the mast assembly closely adjacent to the housing 32.

7 However, the location of the retainer 39 beneath the axle makes installation and removal of the mast assembly very awkward. Whenever it is necessary to replace the mast or to gain access to the front wheels or to the differential for servicing, either the mechanic must reach underneath the truck (which is usually quite close to the ground) to install or-remove the bolts holding the retainer or the truck must be lifted. Either procedure is time-consuming and expensive.

The principal features of the invention are shown in FIGURE 4. A portion of the mast assembly 17 is formed with a downwardly opening concave bearing surface 42 which rests directly on the axle 28. The portion in which the surface 42 is formed may, for example, comprise a bracket 41 formed integrally with or permanently fastened to the main portion 17 of the mast assembly. The opening and bearing surface is approximately semi-cylindrical but obviously should not extend over more than 180 degrees. The bracket 41 is formed with a convex bearing surface 43 above and co-axial with the surface 42. A retainer 44 is formed with a complementary concave bearing surface 45 which engages the surface 43. The retainer 44 is removably fastened to a portion of the frame 12, as will be more fully described, to prevent upward movement of the bracket 41 and the mast assembly 17. 'By this arrangement the mast assembly 17 may be mounted closely adjacent to the differential housing 32 yet may be easily installed or removed because the retainer 44 is in an accessible position above the axle.

Referring now to FIGURE 5, there are shown the two front wheels 13, the front axle 28, and the differential housing 32. It will be understood that an electric motor or a gasoline engine (not shown) is operatively connected to the differential to drive the wheels 13.

As best shown in FIGURE 7, the main side frame member 12 has formed integrally therewith or Welded thereto two additional frame members 51 and 52 to which, in turn, is fastened a forwardly extending frame portion 53. As best shown in FIGURE 6, the frame portion 53 is formed with a downwardly opening semi-cylindrical bearing surface which rests on the upper surface of the axle 28. A complementary retainer 55 engages the lower surface of the axle 28 and is fastened to the frame portion 53 by bolts 56. By this arrangement, the frame of the truck is removably fastened to and supported by the front axle 28.

As best shown in FIGURE 7, the previously mentioned bracket 41 is permanently fastened, for example by Welding, to a cross brace 61 which, in turn, is permanently fastened to the upright portion of the mast assembly 17. Also shown in FIGURE 7 is the previously mentioned downwardly opening concave bearing surface 42. The bracket 41 is formed with a boss 62 extending laterally and substantially parallel to the axle 28 (upward and to the left as viewed in FIGURE 7). The boss 62 is formed on its underside with a continuation of the bearing surface 42 and, on its upper side, with the previously mentioned convex bearing surface 43 co-axial with the surface 42.

The retainer 44 is formed with a concave bearing surface 45 complementary to the convex surface 43 and is also formed with a laterally projecting lip portion 64 having a fiat undersurface. The frame portion 53 is formed with a fiat shoulder portion 65. When the parts are assembled, as shown in FIGURE 8, the concave surface 42 engages and is supported by the upper surface of the axle 28; the surface 45 engages the surface 43; and the lip portion 64 engages the shoulder portion 65. Bolts 66 passing through the lip portion 64 into threaded apertures in the shoulder portion 65 hold the retainer 44 to the frame portion 53.

The foregoing detailed description has illustrated and described only those parts pertaining to the left side of the truck. It will be understood that the right side includes similar brackets, frame portions, retainers, etc. In FIGURE 5 there are shown some of these parts, such as the bracket 41' and the retainers 44 and 55'.

It is apparent that the novel arrangement of the present invention allows the mast assembly to be positioned closely adjacent to the differential housing. No interference between the assembly and the housing occurs when the mast is tilted because the mast is pivoted about the front axle which is concentric with the differential housing. Additionally, the mast assembly may be removed quickly and easily because the retainer 44 and the bolts 66 are in a readily accessible location above the axle.

Although a preferred embodiment of the invention has been described in considerable detail for illustrative purpose, many modifications will occur to those skilled in the art. It is therefore desired that the protection afforded by Letters Patent be limited only by the true scope of the appended claims.

What is claimed is:

1. A lift truck, comprising,

an axle,

a mast assembly,

said mast assembly being formed with a concave cylindrical bearing surface resting on the upper surface of said axle, and

means positioned above said axle for retaining said bearing surface in engagement with said axle.

2. A lift truck, comprising,

an axle,

a mast assembly,

a pair of brackets fastened to said mast assembly,

each of said brackets being formed with a downwardly opening, concave, bearing surface resting on the upper surface of said axle, and

means positioned above said axle for retaining said brackets in contact with said axle.

3. A lift truck, comprising a frame, a

an axle supporting said frame,

a mast assembly,

said mast assembly being formed with a pair of concave bearing surfaces,

said mast assembly being positioned with said concave surfaces engaging and supported by said axle, and

means removably fastened to said frame above said axle for retaining said bearing surfaces in engagement with said axle.

4. A lift truck, comprising,

an axle,

a mast assembly,

said mast assembly being formed with a concave cylindrical bearing surface engaging and supported by said axle,

said mast assembly also being formed with a convex cylindrical bearing surface above and co-axial with said concave surface, and

means cooperating with said convex surface for retaining said concave surface in engagement with said axle.

5. A lift truck, comprising,

an axle,

a frame supported by said axle,

a mast assembly,

said mast assembly being formed with a concave cylindrical bearing surface, not greater than one hundred and eighty degrees in extent, complementary to and engaging the top outer surface of said axle,

said assembly also being formed with a convex cylindrical bearing surface co-axial with and having a greater radius of curvature than said concave surface, and

a retainer removably fastened to said frame,

said retainer being formed with a concave cylindrical bearing surface complementary to and engaging said convex surface.

6. A lift truck, comprising,

a frame,

an axle supporting said frame,

a mast assembly,

said mast assembly being formed with a pair of concave cylindrical bearing surfaces, not greater than one hundred and eighty degrees in extent, complementary to and supported by the top outer surface of said axle,

said assembly also being formed with a convex cylindrical bearing surface co-axial with and having a greater radius of curvature than said concave surface,

means removably fastened to said frame and cooperating with said convex surface for retaining said concave surface in engagement with said axle, whereby said mast assembly is pivotally supported by said axle, and

means for varying the angular position of said mast assembly about said axle.

7. A lift truck, comprising,

a front axle,

a frame supported by said axle,

a mast assembly,

said mast assembly being formed with a pair of semicylindrical concave bearing surfaces,

said mast assembly being positioned with said surfaces engaging and supported by the upper surface of said axle,

said mast assembly also being formed with a pair of convex cylindrical bearing surfaces co-axial with said concave surfaces,

means including concave bearing surfaces removably fastened to said frame and cooperating with said convex surfaces for retaining said assembly in engagement with said axle,

an hydraulic ram mechanism mounted on said frame,

and

means operatively connecting said mechanism to said mast assembly, whereby actuation of said mechanism tilts said assembly with respect to said frame.

8. A lift truck, comprising,

a frame,

a front axle supporting said frame,

a mast assembly,

a pair of brackets fastened to said mast assembly,

each bracket being formed with a downwardly opening, concave, semi-cylindrical, bearing surface resting on the upper surface of said axle,

each bracket including a laterally extending boss formed with a convex cylindrical bearing surface above and co-axial with said concave bearing surface, and

a pair of retainers removably fastened to said frame,

each retainer having a concave cylindrical bearing surface complementary to and engaging one of said convex bearing surfaces.

9. A lift truck, comprising,

a front axle,

a frame,

said frame including first and second portions each formed with a concave, semi-cylindrical, bearing surface engaging said axle,

first and second retainers each including a concave, semi-cylindrical, bearing surface embracing said axle and removably fastened to one of said portions whereby said frame is supported by said axle,

a mast assembly,

a load carriage movably supported by said mast assembly,

first and second brackets fastened to said mast assembly,

each of said brackets being formed with a downwardly opening, concave, semi-cylindrical, bearing surface engaging and supported by the upper surface of said axle, whereby said mast assembly is pivotally sup ported by said axle,

each of said brackets including a boss protruding in a direction substantially parallel to said axle,

each of said bosses being formed with a convex, cylindrical, bearing surface above said concave bearing surfaces formed in said brackets and co-axial therewith, and

third and fourth retainers each removably fastened to one of said frame portions,

each of said third and fourth retainers having a concave, cylindrical bearing surface complementary to and engaging one of said convex surfaces on said bosses.

10. A lift truck, comprising,

a front axle,

a frame,

said frame including first and second portions each formed with a concave, semi-cylindrical, bearing surface engaging said axle,

first and second retainers each including a concave, semi-cylindrical, bearing surface embracing said axle and removably fastened to one of said portions whereby said frame is supported by said axle,

a mast assembly,

a load carriage movably supported by said mast assembly,

first and second brackets fastened to said mast assembly,

each of said brackets being formed with a downwardly opening, concave, semi-cylindrical, bearing surface engaging and supported by the upper surface of said axle, whereby said mast assembly is pivotally supported by said axle,

each of said brackets including a boss protruding in a direction substantially parallel to said axle,

each of said bosses being formed with a convex, cylindrical, bearing surface above said concave, bearing 7 surfaces formed in said brackets and co-axial therewith, third and fourth retainers each removably fastened to one of said frame portions, each of said third and fourth retainers having a concave, cylindrical, bearing surface complementary to and engaging one of said convex surfaces on said bosses, and means for varying the angular position of said mast assembly about said axle. 11. Apparatus according to claim 10 in which said last named means comprises an hydraulic ram mechanism mounted on said frame and operatively connected to said mast assembly whereby actuation of said mechanism tilts said assembly with respect to said frame.

References Cited by the Examiner UNITED STATES PATENTS 2,216,697 10/ 1940 Vossenberg 214672 2,220,450 11/1940 Howell 214-674 2,349,353 5/1944 Johnson 214-674 2,915,210 12/1959 Ehmann 214-674 10 2,926,049 2/ 1960 Remke .308,-21

ANDRES H. NIELSEN, Primary Examiner.

SAMUEL F. COLEMAN, Examiner. 

1. A LIFT TRUCK, COMPRISING, AN AXLE, A MAST ASSEMBLY, SAID MAST ASSEMBLY BEING FORMED WITH A CONCAVE CYLINDRICAL BEARING SURFACE RESTING ON THE UPPER SURFACE OF SAID AXLE, AND MEANS POSITIONED ABOVE SAID AXLE FOR RETAINING SAID BEARING SURFACE IN ENGAGEMENT WITH SAID AXLE. 